Well this is only a suggestion but I suggest uninstalling the AMD drivers for it, redo the installation but use a Custom Installation instead of Typical. In it I think you'll find something like HDMI AUDIO checked, uncheck that, once finished restart your PC, check your audio if it's any better.

Also most of the time the echos you hear are from outdated audio drivers (seriously happened to me during my Warcraft 3 days.)